#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define rep(i, a, b) for (int i = (a); i <= (b); i++)
#define per(i, a, b) for (int i = (a); i >= (b); i--)
#define endl '\n'
const int N = 2e5 + 5;

int n, m;
int a[N];

int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  int t;
  cin >> t;
  while (t--) {
    cin >> n >> m;
    string s, t;
    cin >> s;
    bool res;
    if (m == 0) {
      string t = s;
      reverse(t.begin(), t.end());
      res = s < t;
    } else {
      string t = s;
      sort(t.begin(), t.end());
      if (t.front() == t.back())
        res = false;
      else
        res = true;
    }
    cout << (res ? "YES\n" : "NO\n");
  }
  return 0;
}